Hydraulic mechanism



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v J. D. JOHNSON HYDRAULIC MECHANISM Filed Juhe 1a, 1941 3 Sheets-Sheet 1FIG.

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IM/HVTO? Jay D Johnson ATTORNEYS.

Feb. 1, 1944. J. D. JOHNSON HYDRAULIC 'MECHANISM Filed June 18, 194i 3Sheets-Sheet 2 I ATTORNEYS.

Feb. 1, 1944.

J. D; JOHNSON HYDRAULIC MECHANISM 3 Sheets-Sheet 3 Filed June 18 1941FIG. 3

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INVEWTOR Jay D. Johnson ATTORNEYS.

mama Feb '1, 1944 UN T-go STATES PATENT orrica Jay D. Johnsomleorla,m.,- as... to John- Deere Tractor Company, Waterloo, Iowa, a corporationof Iowa Application rune is. 1941' Serial No. 398,539 Claims. (01.121-465) The present application relates to' hydraulic mechanisms of thetype used for controlling the action of hydraulic lifting cylinders,such as are A more specific object of my invention is con cerned withthe provision of a novel and improved valve mechanism for directing thehydraulic fluid to the lifting cylinder or diverting the same to thereservoir, and also for releasing the fluid which is locked within thecylinder and permitting the same toflow to the reservoir to lower thepiston. Still another object of my invention has to do with theprovision of "a control means for determining the rate of flow of thefluid from the lifting cylinder back to the reservoir. Another object ofmy invention relatesto the provision of an improved mechanism forrelieving the pressure inthe supply duct when the power lift pistonreaches the endof its stroke or otherwise becomes immovable.

A further object of my invention-relates to means for venting thecontrol valve casingto prevent leakage of oil to the outside of thecasing. This is. accomplished by providing apessage in the casing wallleading from the top of the reservoir and communicating with the gearcase on the tractor which houses the mechanls that drives the hydraulicpump.

I Still another object of my invention has to do with the provision ofmounting the pump and valve housing on the governor housing of a tractor or other vehicle and driving the hydraulic pump from the governorshaft. Since the governor shaft usually'runs at high speed, the size ofthe pump required is minimized.

These and other objects and advantagesof my: invention will be apparentto those skilled in the ar't after a consideration of the followingdescription inwhich reference is had to the draw- I 'lngs appendedhereto, in which Figure 1 is a plan view, partly in section, taken alonga line I--I in Figure 2, showing the means for mounting the pump andvalve housing on the governor housing and for driving the hydraulic pumpfrom the governor shaft.

Figure 2'is an elevational view partly in sec tion of a hydrauliccontrol mechanism embodying the principles of the present invention;

Figure'3 is an elgvational view taken in section along a line 3-3 inFigure 2; and

Figure 4 is a fractional elevational view taken along a line 4-4 inFigure}, and showing the controlled by-pass for determining the rate ofreturn of the hydraulic fluid from the power lift cylinder. 1

Referring nowto the drawings, the governor 5 of the tractor is indicatedin its entirety by reference character G and includes a housing I00within which a governor shaft IOI is rotatably supported ina ballbearing I02 carried in the end plate I03 of the housing. The end plateis 1 secured to the housing I00 by bolts I04.

The governor shaft IN is driven through a gear I05, keyed to the shaftand adapted to mesh with a suitable engine driven drive gear (notshown). The governor shaft IN is extended through an aperture I06 in theend plate I03 and has a splined outer end I01, on which is fixedlymounted a pump gear I35, and is enclosed in a pump housing block I08with a second pump gear I35. The latter is mounted on a shaft I03 and isdisposed in mesh with the gear I35.

The valve mechanism, indicated generally *by reference character V,includes a valve casing I30 having an extension I3I, disposed injuxtaposition with thepump housing I00. 'Bolts I32 fixedly secure thecasing extension I3I, the pump housing I08 and the end plate I03together, and

other longer bolts I I I extend through these three parts and engage thegovernor housing I00. The

valve housing I is formed with an inner cham- 30 her I36, whichserves asareservoir from which oil or other fluid serving as-a hydraulic medium,

passes through an opening I31 to the pump gears I35.

Since the governor shaft normally runs at a 35 constant speed, the pumpdelivers oil at a substantially constant volume into a high pressureduct I33 which extends'generaily horizontally through the valve casingI30 and intersects a ver- I tical bore I. At its upper end, the bore I4I 40 communicates'wlth the reservoir I36, and at its lower end belowthe duct I39, it opens into a cylindrical valve chamber I43, formed inan exten-' sion I30 in' the bottom of the casing I30. The.

lower end or the valve chamber I43 is tapped to 45 receive a reducer I45, to which a delivery tube V or conduit I40 is coupled in any suitablemanner.

The delivery conduit I46 is extended to any suitable power unit such asa piston and cylinder (not shown). 'A check valve I50 of the'poppet typeis- 59 adapted toclose upwardly against a valve seat I41 for closingolfcom cation between the delivery conduitl46 and he vertical bore MI. Thecheck valve I50 is urged upwardly toward a closed position by means ofalight spring I36 which seats ina bore in the reducer Ilifand encirclesa guide lug 155 on the check valve I00.

The stem'lil of; the check-valve 150 extends upwardly through thevertical bore I and is re ceived within asocket I5] in thelower end of a60 manually controlled. piston valve, indicatedinits entirety by thereference numeral I58. This manual valve comprises a plunger shaft I59slidable in a bearing lug I6I secured to an internal wall I30a in thevalve housing I30 and extends upwardly out of the casing I30 through asuitable packing gland I62. The lower end of the manually controlledplunger shaft I59 carries a cylindrical'piston valve I65 in which anannular groove I66 is formed. The lower end of the piston valve I65 isarranged to engage a stop I52 in the form of a collar or flange rigidlyfixed to the check valve stem II, but the valve plunger I158 may moveupwardly relative to the check valve I50, and the latterfmay in turnmove downwardly relative to the manually controlled valve I 50.

The valve plunger I58 is manually controlled by means of a hand lever2I0 pivotally connected by means of a pin 2I2 to a standard 2 bolted tothe top' of the valve casing I30. The hand lever 2I0 is swingablevertically on the pivot pin 2I2 and is connected with the upper end ofthe valve plunger shaft I59 through atoggle link 2I3.

When the control lever U0 is raised to the position shown in solid linesin Figure 2, the piston valve I65 is held in the upper portion of thevertical bore I4I above the high pressure supply duct I 39, thuspreventing the oil from flowing upwardly into the reservoir I35, butproviding a path for the oil to flow downwardly through the verticalbore MI. The pressure of the oil forces the check valve I50 to opendownwardly against the yielding action of the spring I56 and'the oilthen flows downwardly through the reducer fitting I into. the deliveryconduit I46 leading to the lifting cylinder.

By moving the handle 2 I 0 downwardly, the piston valve I65 is moveddownwardly in the vertical bore I4I into the lower portion of the latterportion of the vertical bore I4I abovethe supply duct I39, and since theplunger shaft I59 is smaller in diameter than the diameter of the boreI4I, the oil readily flows upwardly through the latter into thereservoir, thus relieving the pressure in the supply duct I39. Thiscausesthe spring I56 to close the check valve I50, locking the oil inthe delivery conduit I46, but by forcing the plunger shaft I59downwardly still further, the

.piston valve I65 engages the stop I52 on the check valve stem I5I andfurther downward movement I of the handle 2 I 0 forces the check valve Iopen, thus allowing the trapped oil in the power lift cylinder and thedelivery conduit I46 to escape upwardly past the check valve, but sincethe piston valve I in this position blocks the vertical bore I, as bestillustrated in Figure 4, the oil must follow a by-pass 200. The by-pass200 coma tapped opening 205 in register with the vertical passage 202.By turning the plug 204 the size of the passage can be adjusted toadjust the rate of flow of the return oil therethrough. Tlfiishas theeffect of cushioning the drop of the piston in below the supply ductI39. This opens the upper When the piston in the main power cylinder(not shown) reaches the end of its lifting or power stroke, or isimmovably blocked during the stroke, continued operation of the pumpgears I35 will cause a sudden rise in pressure in the supply duct I39and delivery conduit I46.

which will result in damage to the mechanism unless this pressure isimmediately relieved. The mechanism for automatically relieving theexcess pressure in the supply duct I39 will now be described. A verticalpassage I10 extends upwardly within the internal wall I30a in the valvecasing I30 from the horizontal supply duct I39. A generally horizontalpassage I1I intersects the vertical passage I10 above the supply ductI39 and extends into communication with a relief chamber I 13. Thepassage I1I is normally obstructed by a relief valve I12, which is urgedby means of a compression spring I14 against the seat I19. Thecompression spring I14 reacts against a plug I8I which is threaded intothe outer end of the relief chamber I13 and is adjustable by turning theplug in its threads to adjust the pressure of the spring I14 against thevalve I12. The spring I14 is sufficiently strong so that I36 through anoutlet I84 of somewhat smaller diameter than the passage I83. Theby-pass duct I83 is controlled by a piston. valve I88 which is slidablewithin a vertical bore I86 formed in the internal wall I30a of the valvecasing I30. The lower end of the vertical bore I86 has an opening I81communicating with the relief chamber I13. Normally there is nohydraulic pressure within the relief chamber I13 since the latterisconnected with the reservoir I35 by means of a hole I of small diameter,and the valve I12 is held closed against normal operating pressures bythe' spring I14. The piston valve I88 is normally held in closedposition with respect to the bypass duct I83 by means of a ball I93engaging an annular groove I92 in the upperportion of the valve I08. Theball I93 is urged into engagement with the groove I92 by means of a coilspring I94 disposed in a. horizontal bore I95 in the internal wall I30aof the casing I30.

As soon as the main power piston reaches the end of its lifting stroke,the hydraulic pressure in the supply duct I39 immediat'elyrises, therebyforcing the relief valve I12 away from its seat the cylinder as the loadis being lowered. The

plug 204 can be locked in any desiredposition of adjustment by means ofa pair of lock nuts 206.

no against the action of the spring 114, whereupon the pressure in therelief chamber I13 also rises, causing oil to flow into the verticalbore I86 through the opening I81, forcing the piston valve I88 upwardlyand thus opening the by-pass duct I83 to the reservoir I36. The detentball I93 readily yields to the oil pressure against the lower end of thepiston valve I88, after which the movement of the piston I88 upwardlywithin the bore I86 is very rapid, since the oil pressure is assisted bya coil spring I89 which bears against the lower end ofthe piston I88 andreacts against the lower end of the bore I86 around the edge of the boreopening I81.

- The piston valve I88 rises against a stop in the form of a bushing I98which threads into the top of the vertical bore I86 and has anopeningtherein for receiving a valve stem Isl extending upwardly from the upperend of the piston valve As soon as the valve I88 opensthe by-pass duct I83 to the reservoir I35, the pressure against the relief valve I12 isrelieved, thereby causing the latter to close under the action of thespring Ill. The pistonvalve I88 is retained in raised position, however,by the spring I88 and also by a slight pressure in the by-pass duct I83existing due to the fact that the outlet I84 is of smaller diameter.

The piston valve I88 is returned to closed position by an arm -2I6supported on a collar 2I5 which is fixed to the valve plunger shaft I58.The arm 2I8 overlies the upper end of the valve stem I81, so that whenthe valve operating lever 2 I8 is lowered the arm 2 I 6 engages thevalve stem I81 and forces the valve back to the closed position shown inFigure 2.

The operation of the valve mechanism V, as described above, issubstantially as follows: In Fig ures 1 and 2, the parts are shown inthe positions they occupy when the pump I is'iorcing oil or other fluidthrough the delivery pipe I48 to the power cylinder, thus causingthelatter to lift the load or otherwise move against the'reaction of theload. At this timeit will be noted that the manually operable handle 2I8is in raised position, thus holding the piston valve its in the verticalbore HI above the supply. passage I38 and thus closing oil thecommunication with the reservoir I38. The lifting movement can beinterrllpted at any time by lowering the control handle 2I8 and thusdropping the piston valve I85 into the portion of the bore Ill belowthesupp y passage I39, thus opening the upper portion of the vertical boreIll to the reservoir I88, relieving the pressure in the supply duct andthereby permittin the spring I to reseat the check valve I58, to holdthe load in raised position. By forcing the handle 58 downwardly stillfurther, the piston valve I85 engages the stop member I52 on the checkvalve stem I5I and 8 opens the check valve I58, thereby allowing the,iiuid to escape upwardly past the check valve I58 and aroimd theby-pass passage 288. The load can be raised to the limit or movement ofthe main piston by raising the control handle 2I8 and leaving the latterin raised position. As described in detail above, when the main powerpiston reaches the end of its power stroke, the pressure in the supplyduct I88 rises abruptly, opening the relief valve I12 and then forcingthe by-pass valve I88 upwardly to open the by-pass duct I88 to thereservoir. This relieves the pressure in thesupply duct I88 and allowsthe relief valve I12 to close. To lower the load from the extreme raisedposition. the-control handle 2" is lowered until the piston valve 45engages the avoided by allowing the oil to flow through the groove I88into the delivery duct I46 by way of the ducts 283, 282, 28I and throughthe check valve I58.

A vent hole 228 extends upwardly through the top of the reservoir and isconnected in communication with a downwardly inclined duct 22I formed ina wall of the casing I38 by, a recess 222 in the bottom of the controllevel supporting standard 2| I. The lower end of the passage 22I has anopening ,223 disposed in register with an aperture in the side of thegovernor G. Thus any oil that escapes through the vent hole 228 becauseof foaming, splashing, or the like, isconducted to the governor gearcase, with the result that the outside of the casing I38 is kept cleanand dry.

I claim:

1. In hydraulic mechanism, a casing provided with a cylindrical borecommunicating at one end with a reservoir, a delivery conduit incommunication with the other end of said bore. a supply duct connectedin communication with the intermediate portion or said bore. a pistonvalve slidable in said bore to opposite sides of said supply duct, acheck valve positioned to obstruct flow of fluid from said deliveryconduit to said bore. means for engaging said piston valve with saidcheck valve to open the latter when said piston valve is moved to aposition between said stop I52 on the check valve and opens the latter.

This movement'oi the valve plunger shaft I58 causes the arm 2" to engagethe valve stem I81, forcing the valve Ill back to its closed position,after which the output of the pump flows upwardly. through the bore Illfrom the supply duct I28 and into the reservoir I 85.

If it were not for the groove I 88' in the piston valve I85, the latterwould block the high pressure duct I 88 every time it was moved fromlowering said delivery in: a valve bore, and having supply duct and saiddeliver conduit, and a bypass duct connected with said bore at oppodtesides of saidpiston valve when the latter is in said position.

2. The combination set forth in claim i,'with the further provision ofadjustable valve means in said by-pass duct {or controlling the flow offluid therein. v

3. In hydraulic mechanism, avalve casing hava reservoir duct and adelivery duct communicating with said valve bore at oppositeendsthereof, respectively, a high pressure supply duct connected incommunication with said valve bore intermediate of the ends of thelatter, a valve piston slidable through said bore to either side of saidsupply duct, said piston having a relief passage through which fluidfrom said supply duct can flow during the time said piston moves overthe latter, and a bv-pass duct in said casing disposed in register withsaid relief passage and connected in communication with said deliveryduct for conductin: fluid therebetween when said piston is in a positionblocking said supply duct.

4. In hydraulic mechanism, a valve casing having a valvebore, and havinga reservoir ductand a delivery duct communicating with said valve boreat opposite eids thereof, respectively, a high pressure suppy uctconnected in communicatifonhwilth said valve bore 0 e atter, a valvepiston slidable through said bore to either side or said supply duct,and a by-pass passage in said casing interconnecting duct and said upplyduct, for exhausting said delivery. duct with said supply duct into saidreservoir duct whenvsaid valve m is in a position between said deliveryduct and said supply duct. 5. The .combination set forth the furtherprovision in by-pass a 9.1;

in (318-1111 4, with e i'or controlling the flow an. JOHNSON.

intermediate of the ends of dj stable valve means

